Gas check for projectiles

Abstract

A projectile that includes a body and a bearing surface that extends cylindrically across a portion of the body. A gas check is formed in the bearing surface that includes at least one relief band. The relief band extends annularly through the bearing surface. A profile of the relief band is bilaterally symmetrical about a central plane, and a shape of the profile on a side of the central plane is defined by a plurality of intersecting segments. The segments include a central segment portion located at a lowest point of the profile, an upper side segment located at a highest point of the profile, a rising segment that extends at an acute angle from the central segment portion toward the upper side segment, and a curved segment that connects the upper side segment and the rising segment.

What is claimed is: 
     
       1. A projectile, comprising:
 a body having a length and a width; 
 a bearing surface that extends cylindrically across a portion of the body in a direction of the length of the body; and 
 a gas check formed in the bearing surface, the gas check including at least one relief band, the at least one relief band extending annularly through the bearing surface in a direction of the width of the body, 
 wherein, in a planar cross-section of the at least one relief band taken through the width of the body and extending along the length of the body, a profile of the at least one relief band is bilaterally symmetrical about a central plane, and a shape of the profile on a side of the central plane is defined by a plurality of intersecting segments, including:
 a central segment portion located at a lowest point of the profile, 
 an upper side segment located at a highest point of the profile, 
 a rising segment that extends at an acute angle from the central segment portion toward the upper side segment, and 
 a curved segment that connects the upper side segment and the rising segment. 
 
 
     
     
       2. The projectile according to  claim 1 , wherein the at least one relief band includes at least two relief bands, and
 wherein the gas check further includes a drive band disposed between the at least two relief bands, the drive band having an outer diameter equivalent to an outer diameter of the bearing surface. 
 
     
     
       3. The projectile according to  claim 1 , wherein a dimensional size of the segments of the plurality of segments is based, at least in part, on a rifling depth of a barrel sized to correspond with use of the projectile. 
     
     
       4. The projectile according to  claim 3 , wherein the dimensional size of the segments of the plurality of segments is further based by increasing the rifling depth of the barrel by 0.001 inch. 
     
     
       5. The projectile according to  claim 3 , wherein the dimensional size of the central segment portion is determined by dividing in half a value calculated as 1.975 times the rifling depth of the barrel. 
     
     
       6. The projectile according to  claim 3 , wherein a radius of the curved segment is determined by multiplying 7.5 times the rifling depth of the barrel. 
     
     
       7. The projectile according to  claim 3 , wherein a length of the shape of the profile on the side of the central plane is determined by dividing in half a value calculated as 18.125 times the rifling depth of the barrel. 
     
     
       8. The projectile according to  claim 1 , wherein the acute angle at which the rising segment extends is about 8.5 degrees. 
     
     
       9. The projectile according to  claim 1 , wherein the gas check extends across a portion of the bearing surface such that a sequence of a plurality of relief bands are formed between drive bands having a diameter equivalent to an outer diameter of the bearing surface.